Nonlinear pattern of the emergence of white matter hyperintensity in healthy Han Chinese: an adult lifespan study

White matter hyperintensities (WMHs) are prevalent in the older adult and are often accompanied by cognitive decline and an increased risk of dementia. However, the roles of WMHs in the periventricular white matter and deep white matter regions in the aging process remain controversial. This study aimed to investigate the WMH burden across the adult lifespan and determine the interrelationships among age, WMH, and cognition. The present study included 312 healthy individuals aged 21-89 years who received structural magnetic resonance imaging and cognitive assessments. Periventricular WMH (PVWMH) and deep WMH (DWMH) volumes were computed and fitted using different regression models to evaluate the trajectory of WMH changes across the lifespan. Our findings support that the changes in WMH volume in the healthy population follow a nonlinear pattern with age, especially in PVWMH. With 2-mediator mediation analysis, we further suggest that the effect of age on the cognitive performance is mediated only by PVWMH. Conclusively, the increased PVWMH, but not DWMH, plays a major role in predicting cognitive aging in healthy adults.